Define acid rain and trace the steps in its formation.

Explanation

Acid rain results when sulfur dioxide `(SO_2)` and nitrogen oxides `(NO_X)` are emitted into the atmosphere and transported by wind and air currents. The `SO_2` and `NO_X` react with water, oxygen and other chemicals to form sulfuric and nitric acids. These then mix with water and other materials before falling to the ground.